Development of A Land-River-Ocean Coupled Model for Compound Floods Jointly Caused by Heavy Rainfalls and Storm Surges in Large River Delta Regions

Abstract. Simultaneous or sequential occurrence of different flood processes, including extreme storm surges and heavy precipitation, tends to trigger compound floods, which are often destructive to life and property. However, numerical models that fully represent the effect of various flood processes and their interactions have not yet been firmly established. In this study, a coupled land-river-ocean model is developed that considers storm surge, storm wave, astronomical tide, river flow, and precipitation. The coupled model is applied to the simulation of compound floods induced by tropical cyclones in the Pearl River Delta. The numerical results are shown to agree well with observations on river flow, ocean surface elevation, and inundation area. An attribution analysis implies that contributions from land, river, and ocean processes are usually all important in a compound flooding event. The completeness of the coupling method significantly affects the numerical accuracy.